The first objective of the proposed research is to continue studies on the metabolism and toxicity of dihalomethanes and, particularly, dichloromethane. These studies will examine the cellular interactions of reactive intermediates of dichloromethane and the metabolism of dihalomethanes by purified enzymes will also be studied. Furthermore, the mutagenicity of dihalomethanes will be investigated along with the metabolism and toxicity of dichloromethane in the maternal-fetal unit. Finally, the behavioral toxicity of dichloromethane will be studied. The second objective is to study the metabolism and cellular interactions of a halogenated flame retardant, tris(2,3-di-romopropyl)phosphate.